The correct option is B P-2; Q-4; R-1; S-3
The carboxylic acid group has general structure formula R−O||C−O−H.
An alkyne is one where there is a triple covalent bond between two carbon atoms.
An ester is an organic compound with general structure formula R−O||C−O−R′.
A ketone is an organic compound with structural formula R−O||C−R′.
Here, R = alkyl group.